Welcome Guest - Sign Up today
Welcome Guest - Sign Up today


No announcement yet.

Safely Cutting a fuel tank

  • Filter
  • Time
  • Show
Clear All
new posts

  • Safely Cutting a fuel tank

    Oh, my tank work!!.have other posts on diff topics of the rebuild/replacement...But now more!

    Ive got my new pick-up parts and bungs & welder ready...and I have to bring him my tanks and parts.

    My Original tank is 155 Gallon, out of the boat and now emptied. It will eventually be Scrapped totally. I have a newer Marine certified baffled tank I have to rework the bungs/ports/ fill etc, going into the boat when reworked.

    I want to cut out out a 8" circle from the top of the old tank, that has the 1 1/2 Inlet, 5/8 vent, and the sender opening. I'd like to take this area out as a "plate", and have the welder install it in my "new" tank. I have it all measured out, so things line-up with access deck plates. Is this even a good idea?

    SO, The 155 is empty...I was gonna fill it up with water/soap and rinse it out and let water flow thru it for awhile to get rid of any fumes. Regardless I will do this for safety.

    BUT the ?....To remove a portion of this tank, after serveral washings/rinses...can I fill it up to the top (literally) and use a Jig saw to cut out the area I want? I"m thinking if there is no air in it and full of water, it shold be ok after the rinsing/washing.

    I do alot but havent messed with tanks before...Not an area I want any surprises. Treading carefully.

  • #2
    Aluminum doesn't spark. However the jigsaw brushes do. Use your nose after the washout, if you can't smell gas, start cutting. No fumes, no boom.
    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.


    • #3
      Assuming your tank is aluminum, you should be good, especially with all of your prep. Aluminum doesn't spark. If steel, you should still be OK. Fumes are the risk.

      If you want to make a pretty hole, you may want to buy or rent one of these. ...I'm fixing to do my own duct work on a basement remodel, and will buy one for sure. It works with a cordless drill. One hole to center the pilot, then drive the cutter bit with your cordless. ....don't know the metal thickness capacity though. Slow feed normally compensates for thick metal.

      Click image for larger version

Name:	cutter.JPG
Views:	1
Size:	7.7 KB
ID:	10843050
      '96 Larson 174 SEI BR. 4.3LX 4 bbl Weber s/n 0F786604. Alpha One Gen II s/n 0F709315


      • #4
        wax the blades. also, you can weld-prep with a router

        I used to weld/braze fuel tanks when I was restoring old 70's vintage muscle cars prior to the plethora of cheap aftermarket tanks. we used to fill them up with water, then weld in the patch

        fill the tank up with water, and have at it with the saw.

        however remember..... once you modify the tank, its no longer certified.
        Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

        1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

        Past Boats
        1970 Wooster Hellion - Merc 9.8
        2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
        1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

        What’s behind you doesn’t matter.Enzo Ferrari


        • #5
          Thanks all, was skiddish today messing with it. Had to back off and get on here!

          Good point on the tool Brushes...I dont even mind cutting that area off the top by hand actually-not that big...Just no Booms.

          Sounds like I should be ok, if rinsed out several times with Dawn, then filled to the top with water while I take that 8-12" area out.

          Will do the same with the newer tank prior to taking it, and the parts and donor "Plate" to my welder guy.

          appreciated as always!


          • #6
            I have been reading about your plans to cut into your tank find some one local who works on fuel tanks and find out who cleans tanks for them prior to welding repairs! There will be some one who steam cleans and uses a sniffer to check for explosive gases This is the only truly safe way to go about it. I would never have touched a fuel tank at work without this being done.



            • #7
              My brother in law used to braze tanks that had holes in them. He would throw the tank on his tailgate, run a hose from the exhaust pipe I to the tank and let the truck run for an hour. Grab the torch and braze it up. Scary. I stood far away.
              If ya can't fix it with a hammer,ya got yourself an electrical problem.


              • #8
                Originally posted by Grub54891 View Post
                My brother in law used to braze tanks that had holes in them. He would throw the tank on his tailgate, run a hose from the exhaust pipe I to the tank and let the truck run for an hour. Grab the torch and braze it up. Scary. I stood far away.
                I know three people that do it this way and they are all still alive.


                • #9
                  Sign up today
                  Have heard of that exhaust approach as well....Been reading more of this. I now believe twice rinsed with soapy water, then completely filled with water while I "hand" cut out the piece I need....should be safe.

                  WIll report back Sat.